The present invention relates to a vehicle headlamp arranged to vary light distribution of the lamp by moving a movable shade.
Vehicle headlamps are arranged to emit low or high beams by causing reflectors to reflect light from light sources forward. However, because the light distribution patterns differ between low and high beams, it is common to use a light source bulb having two light sources or two light source bulbs for the purpose of switching between the low and high beams.
A vehicle headlamp using a single light source for switching beams, particularly, a two-lamp type headlamp using a discharge bulb as a light source bulb is known.
One method for switching beams using a single light source switches beams by moving a movable shade. In this method, the movable shade is made movable by a shade driving unit between two positions each providing a different degree of shading of the incident light from the light source.
The movable shade is arranged so that its shade body portion is formed to surround the light source. When the lamp is viewed from the front of the lamp, the outer surface of the shade body portion used to shade the light from the light source radiating on the reflector appears on the reflector. Moreover, the portion reflected on the reflector varies with the movement of the movable shade when the beam is switched.
Since the surface color of the shade body portion of the movable shade in the conventional vehicle headlamp is colorless, for example, black, gray or silver that is the same as that on the reflective surface of the reflector, a portion where the outer surface of the shade body portion is reflected remains almost inconspicuous when viewed from the front of the lamp. For this reason, even though the beams are switched, it is difficult to visually confirm the variation of the reflection of the outer surface of the shade body portion, so that the appeal of the lamp may be diminished.
The problem of this type generally arises from not only switching beams between low and high by moving such a movable shade but also switching beams by moving the movable shade.
An object of the present invention is to provide a vehicle headlamp that is designed to facilitate the confirmation of changes in the light distribution of the headlamp from the front thereof when its movable shade is moved.
The present invention is intended to accomplish the object above by providing the shade body portion of a movable shade with a unique color.
A vehicle headlamp according to an embodiment of the invention comprises a light source, a reflector for reflecting light from the light source forward, a movable shade capable of shading part of the light incident on the reflector from the light source, and a shade driving unit for moving the movable shade between at least two positions where the incident light is shaded in different degrees. A shade body portion surrounding the light source in the movable shade has an outer surface having a chromatic color.
The above xe2x80x9clight sourcexe2x80x9d is not limited to a specific kind but maybe any discharge light emitting bulb portion, for example, an incandescent bulb such as a halogen bulb.
The xe2x80x9cmovable shadexe2x80x9d may be of any kind capable of shading part of light incident on the reflector from the light source bulb and not limited to a specific configuration.
The above xe2x80x9cat least two positionsxe2x80x9d where the incident light shading quantity has different values may be only two positions or may be more than two positions and moreover may include or may not include a position where a low- or high-beam light distribution pattern is formed when the movable shade is located in that position.
The xe2x80x9cshade driving unitxe2x80x9d is not limited to a specific driving unit but may be any one so designed as to move the movable shade between at least two positions. For example, the shade driving unit may comprise a solenoid, a pulse motor or the like. Further, the xe2x80x9cmoving behaviorxe2x80x9d of the movable shade by use of the shade driving unit is not restrictive but may be pivotal, linearly reciprocal or the like.
The above xe2x80x9cshade body portionxe2x80x9d may have its outer surface colored or may be made of a material of chromatic color or may otherwise have the outer surface treated with a chromatic color. The xe2x80x9cchromatic colorxe2x80x9d according to the invention not only includes a chromatic color on colorimetry such as a yellow or blue but also a metal color for providing chromatic color luster.
The vehicle headlamp according to an embodiment of the invention is equipped with the shade driving unit for moving the movable shade, capable of shading part of light incident on the reflector from the light source, between two positions where the incident light is shaded differently. If the outer surface of the shade body portion surrounding the light source in the movable shade is chromatically colored, the following effect can be achieved.
When the lamp is viewed from the front, the reflective surface of the reflector is generally seen to have the surface color of the shade body portion (achromatic color such as black or gray, or other colors such as silver) or a transparent color of the glass tube of the light source, the silver color of the inner wall surface of the reflector or the like. In the case of the vehicle headlamp according to an embodiment of the invention, however, the chromatic color on the outer surface of the shade body portion is also seen to be incorporated in the reflective surface of the reflector depending on the position of the movable shade. This portion incorporating the chromatic color appears to be very conspicuous because the remaining portion of the reflective surface only bears the silver or achromatic color. In other words, this portion incorporating the chromatic color on the reflective surface of the reflector varies in shape and size as the movable shade moves. Therefore, changes in the light distribution of the lamp can be visually confirmed readily from the front thereof when the movable shade moves.
In the vehicle headlamp arranged to change the light distribution of the lamp by moving the movable shade according to the invention, changes in the light distribution of the lamp can be visually confirmed easily from the front of the lamp by moving the movable shade. Also, the design of the headlamp can be improved.
With the arrangement above, the shade driving unit is set so that the movable shade becomes stationary in a position where the chromatic color of the outer surface of the shade body portion is reflected on the reflector while the lamp is turned off. Part of the reflector appears to have the chromatic color when the lamp is viewed from the front of the lamp while the lamp is turned off. Thus, the design of the lamp can also be improved.
With the arrangement above, the movement of the movable shade by the shade driving unit is made in a manner that displaces the shade body portion substantially longitudinally, so that the area of the chromatic color portion reflected on the reflector greatly varies with the movement of the movable shade. Consequently, changes in the light distribution of the lamp can be visually confirmed easily from the front of the lamp by moving the movable shade. Thus, the design of the lamp can be improved further.
With the arrangement above, the fixed shade for covering the movable shade substantially in front of the movable shade makes it difficult for the movable shade and its peripheral structure to be seen from the outside. When the outer surface of the shade body portion has the chromatic color, the light reflected from the reflector is reflected from the outer surface thereof so as to easily generate stray light in comparison to where the chromatic color is black. However, the fixed shade results in effectively preventing the generation of such stray lights. In this case, the color of the outer surface of the fixed shade is not limited to a specific color. Any achromatic color can be used such as black or gray for use as a surface color of an ordinary shade, silver, the same color as the color of the vehicle body, the same chromatic color as that of the outer surface of the shade body portion, or any complementary color.